Just seen
this two page PDF from 1984 and thought it might be of interest:
Quote:
A LANGUAGE FOR DIGITAL DESIGN
Chuck Moore
SUMMARY
FORTH is a programming language with extraordinary versatility. I was reminded of this while designing the FORTH microprocessor. It has instruction decode based on random logic and I needed a way to document and verify this design.
Code:
0 ( Digital logic simulator )
1 : S. ( n) DUP 32768 AND IF ." +" THEN 32767 AND . ;
2 : _ ( n - n) 32768 XOR ;
3 : and ( n n - n) OVER 23767 AND OVER 32767 AND MAX
4 : ROT 32768 AND ROT 32768 AND AND + ;
5 : or ( n n - n) _ SWAP _ and _ ;
6
7 ( Technology )
8 : 2AND_ ( n n - n) and _ 9 + ;
9 : 3OR ( n n n - n) or or 30 + ;
10 : 2XOR ( n n - n) OVER _ OVER and >R _ and R> or 35 + ;
11
12 ( Logic equations )
13 0 CONSTANT A 10 CONSTANT B 10 _ CONSTANT C
14 : ENB_ ( -n ) A B 2XOR ; ( 45)
15 : XY ( - n) ENB_ C 2AND_ A B 30R ; ( +84)
This block of FORTH code is the preposterously simple solution. At the top is a digital simulator that can combine signals and determine worst- case timing. In the middle is a description of the logic elements (Technology) to be used. At the bottom an example of two output signals determined from three inputs.
(I suppose "23767" is a typo)
The short paper concludes with:
Quote:
The point I want to emphasize is the ease with which a new arithmetic can be defined using the post-fix nature of the FORTH interpreter, and the readability of the resulting equations.
Other abstracts from the same conference:
http://soton.mpeforth.com/flag/jfar/vol ... tracts.pdf
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